Mature cystic teratoma simulating caesarean scar pregnancy: a rare case report

Abstract

Mature cystic teratomas (dermoid cysts) are common benign ovarian germ cell tumours that usually demonstrate characteristic radiological features. However, coexisting pelvic pathology and altered postoperative anatomy may occasionally result in misleading imaging appearances, posing a significant diagnostic challenge. Caesarean scar pregnancy (CSP) is a rare but potentially life-threatening form of ectopic pregnancy that requires prompt recognition and appropriate management. We report the case of a 30-year-old multiparous woman with a previous lower segment caesarean section who presented with heavy prolonged menstrual bleeding and foul-smelling vaginal discharge. Initial ultrasonography suggested a left ovarian dermoid cyst with bilateral hydrosalpinx. However, magnetic resonance imaging (MRI) performed at a tertiary centre demonstrated an extrauterine gestational sac containing fetal skeletal structures communicating with the uterine cavity through a previous caesarean scar, raising suspicion of CSP. The absence of pregnancy-related symptoms and a negative serum β-human chorionic gonadotropin level prompted further clinical evaluation. Exploratory laparotomy revealed a left ovarian mature cystic teratoma densely adherent to the previous caesarean scar, bilateral pyosalpinx, extensive pelvic adhesions, and a uterine scar defect with scar endometriosis. Histopathological examination confirmed the diagnosis. This case illustrates an unusual diagnostic pitfall in which the combined presence of calcified components within the dermoid cyst, a previous caesarean scar defect, dense pelvic adhesions, bilateral pyosalpinx, and scar endometriosis created an MRI appearance closely resembling a CSP. Careful clinicoradiological correlation and integration of laboratory findings remain essential to avoid misdiagnosis and guide appropriate surgical management.